Paper 13: Infra-tubercular versus retro-tubercular slope-correcting high tibial osteotomy in revision anterior cruciate ligament reconstruction: comparative survivorship, stability, alignment, and healing

Objectives: To compare infra-tubercular versus retro-tubercular slope-correcting high tibial osteotomy performed with revision anterior cruciate ligament reconstruction across prespecified outcomes: (1) graft survivorship (global failure by Kaplan-Meier), (2) anterior knee stability quantified by instrumented laxity at 2 months, 1 year, and 2 years, (3) patient-reported outcomes (Knee injury and Osteoarthritis Outcome Score subscales and International Knee Documentation Committee) from baseline to 2 years, (4) radiographic alignment parameters-posterior tibial slope and hip-knee-ankle angle-and (5) complications, reoperations (including hardware removal), and time to bone healing. A secondary aim was to delineate technique-specific trade-offs between stability/alignment and healing/implant management to inform procedure selection. We hypothesized that survivorship and improvements in patient-reported outcomes would be comparable between techniques, that the infra-tubercular approach would demonstrate lower instrumented laxity and smaller changes in hip-knee-ankle angle, and that the retro-tubercular approach would be associated with faster bone healing and fewer hardware removals.
Methods: Retrospective matched cohort (2016-2024) of adults undergoing revision anterior cruciate ligament reconstruction with slope-correcting high tibial osteotomy. Exclusions included concomitant coronal realignment, multiligament reconstruction (posterior cruciate ligament or posterolateral corner), meniscal allograft transplantation, large cartilage allograft, and repeat slope osteotomy. The primary endpoint was global failure, defined as revision surgery or instrumented anterior laxity greater than 5 mm. Secondary endpoints were instrumented laxity at 2 months, 1 year, and 2 years; patient-reported outcomes (Knee injury and Osteoarthritis Outcome Score subscales and International Knee Documentation Committee) from baseline to 2 years; radiographic hip-knee-ankle angle and posterior tibial slope; complications; reoperations including hardware removal; and time to bone healing. Posterior tibial slope was measured on lateral radiographs. Hip-knee-ankle angle was measured on full-length standing radiographs. Group comparisons used t tests or χ²/Fisher exact tests, paired tests for within-group change, and Kaplan-Meier with log-rank testing; α=0.05.
Results: We analyzed 107 patients (infra-tubercular [IKO] n=49; retro-tubercular [RKO] n=58). Median global failure-free survival was 43.3 months for IKO and 39.0 months for RKO. The log-rank p value was 0.503.Instrumented anterior laxity (mm) at 2 months was 2.4+-2.1 for IKO and 3.3+-2.0 for RKO (p=0.034). At 1 year it was 3.5+-2.3 and 4.8+-2.7 (p=0.010). At 2 years it was 4.0+-2.9 and 5.8+-4.2 (p=0.013).Patient-reported outcomes (KOOS subscales, IKDC) improved from baseline to 2 years within each group (all p<0.001). Between-group differences in change were not significant (all p>0.05).Radiographs showed posterior tibial slope change (ΔPTS, degrees) of −7.9+-1.7 for IKO and −8.2+-1.6 for RKO (p=0.350). Hip-knee-ankle angle change (ΔHKA, degrees) was +0.45+-0.58 for IKO and +1.32+-1.20 for RKO (p<0.001).Overall complication rates were 14.3% for IKO and 12.1% for RKO (p=0.735). Hardware removal occurred in 38.8% for IKO and 17.2% for RKO (p=0.016). Time to bone healing (months) was 4.0+-0.9 for IKO and 3.2+-0.6 for RKO (p<0.0001).
Conclusions: In this matched cohort of revision anterior cruciate ligament reconstruction with slope-correcting high tibial osteotomy, infra- and retro-tubercular techniques yielded comparable survivorship and improvements in patient-reported outcomes with similar magnitudes of posterior tibial slope reduction. Distinct performance profiles were observed: the infra-tubercular technique was associated with lower instrumented anterior laxity at serial follow-ups and smaller changes in hip-knee-ankle angle, whereas the retro-tubercular technique was associated with fewer hardware removals and a shorter time to bone healing. These findings support tailoring the osteotomy level to the principal clinical objective: infra-tubercular when prioritizing anterior stability and coronal alignment preservation, and retro-tubercular when prioritizing accelerated union and reduced implant-related procedures. Given the similar survivorship and symptom gains, shared decision-making should weigh stability versus healing trade-offs against patient biomechanics, activity demands, and rehabilitation timelines. Prospective studies are warranted to confirm these trade-offs, refine patient selection, and define slope-correction targets that optimize outcomes.